Antipyrine clearance in surgical patients maintained on hypocaloric peripheral parenteral nutrition

Antipyrine clearance (CLAP) constitutes a sensitive indicator of hepatic microsomal enzyme activity providing specific information on hepatic function. The purpose of this study was to evaluate the influence of hypocaloric peripheral parenteral nutrition on CLAP in patients receiving nutrition support after elective surgery.

CLAP was measured in 15 patients before elective gastrointestinal surgery and 6 days after the surgery. Antipyrine (1 g) was administered orally, and CLAP was determined by the one-sample method. Subjects received a postoperative 786 kcal/d regimen providing 66 g of amino acid per day and 133 g of glucose per day for 5 days. Nutritional status was evaluated by anthropometric parameters. A control group of 15 patients received no postoperative hypocaloric peripheral parenteral nutrition but received conventional fluid therapy.

Mean CLAP was increased by 61% (0.66 +/- 0.06 mL/min.kg-1 body wt vs 0.41 +/- 0.05 mL/min.kg-1 body wt in the preoperative period; p < .001), and antipyrine half-life was reduced by 42% (10.9 +/- 1.0 hours vs 18.9 +/- 2.0 hours; p < .001) after 5 days of hypocaloric peripheral parenteral nutrition. No significant modification was shown among control patients in CLAP (0.54 +/- 0.07 mL/min.kg-1 body wt vs 0.46 +/- 0.05 mL/min.kg-1 body wt in the preoperative period) or in antipyrine half-life (14.0 +/- 1.4 hours vs 16.5 +/- 1.8 hours). No significant correlation was observed between CLAP changes and those for the nutritional status of the patients.

The results of our study indicate that oxidative drug-metabolizing capacity is increased in surgical patients maintained on hypocaloric peripheral parenteral nutrition. Clinicians should be conscious of the potential of this effect for altering the efficacy or toxicity of many therapeutic agents.